An excavator boom is a component used to operate an excavator, a piece of heavy machinery used for digging holes or otherwise moving large amounts of material. The excavator usually consists of a base with tracks or treads attached to rotating wheels, as well as a unit known as the house that rotates 360 degrees so the operator can access material on all sides of the machine without repositioning the entire unit. The excavator boom extends off the front of the house, and it usually consists of two pieces that articulate for better reach.

A bucket is mounted to the end of the excavator boom. This bucket is responsible for doing the digging as well as for containing the materials to be moved. All components of the excavator boom as well as the bucket itself are controlled by hydraulics; an outer stanchion filled with fluid — usually some sort of oil — can be pressurized, thereby causing an internal piston to push forward. When the pressure is released, the piston will retract. In this way, the two parts of the excavator boom as well as the bucket can be controlled from the operator's cabin of the machine.

Steel is usually used to construct the very large excavator boom arms. The two sections of the arm are hinged, and articulation is possible thanks to bearings or bushings at the connection points between the two boom arm sections. The hydraulics are mounted at various points along the length of the arms; they are strategically positioned to allow for the most efficient movements that will extend the arm as far as possible. other hydraulics are mounted near the bucket to extend or retract that attachment. These too will be mounted to allow for the most extension and retraction possible.

Other attachments can be affixed to the excavator boom. A quick-coupling design allows the user to switch out the bucket for another attachment to suit a particular job, thus adding to the versatility of the machine. Other attachments may include a jackhammer attachment, compaction wheels, cutting wheels, grappling arms, and so on. Grappling arms are especially useful for picking up or otherwise manipulating logs and trees. A jackhammer attachment is useful for breaking up concrete or asphalt quickly and effectively. Excavator rakes are available, as are amphibious attachments for dragging waters. Other specialty attachments for highly specialized applications can be made custom or may be made through limited production.